In recent years, as advances have been made to allow the miniaturization of semiconductor elements, further miniaturization for the lithography steps used in their production has been desired. The background of the rapid progress of miniaturization includes an increase in NA of projection lenses, an improvement in the performances of resists, and a shortening of the wavelength.
Under such circumstances, many examples are reported in which polyorganosilsesquioxane having a phenolic hydroxyl group is used for fine processing. Polyorganosilsesquioxane is characterized as being soluble in aqueous alkaline solutions due to the phenolic hydroxyl group included therein (see, Patent Document 1).
Whereas, a trilayer resist process in which an intermediate layer is provided for forming a fine pattern was also proposed. In particular, a ladder silicone copolymer having a phenolic hydroxyl group for use in an antireflection film has also recently been reported. In this report, the antireflection film is formed with an ArF laser particularly used in fine processing (see, Patent Document 2).
However, polysilsesquioxane having a phenolic hydroxyl group cannot form an antireflection film because of its high light transmittivity at a far ultraviolet ray absorption with a wavelength of 248 nm as in the KrF exposure. Therefore, to provide an alkali-soluble siloxane material that has a phenolic hydroxyl group, and exhibits absorption at around the ultraviolet ray with a wavelength of not less than 200 nm has been desired.    Patent Document 1: Japanese Unexamined Patent Application Publication No. Hei 08-334900    Patent Document 2: Japanese Unexamined Patent Application Publication No. 2004-341479